Effect of boron on the crystallization of amorphous Si–(B–)C–N polymer-derived ceramics

• Published in: Journal of non-crystalline solids 2009-11, Vol.355 (48), p.2381-2389
• Main Authors: Tavakoli, A.H., Gerstel, P., Golczewski, J.A., Bill, J.
• Format: Article
• Language: English
• Subjects: Amorphous ceramics; Cross-disciplinary physics: materials science; rheology; Crystallization; Exact sciences and technology; Growth from solid phases (including multiphase diffusion and recrystallization); Materials science; Methods of crystal growth; physics of crystal growth; Nanocrystals; Phases and equilibria; Physics; Thermodynamics; X-ray diffraction
• ISSN: 0022-3093; 1873-4812
• DOI: 10.1016/j.jnoncrysol.2009.08.010

Amorphous Si–(B–)C–N polymer-derived ceramics (PDCs) with a boron content ranging from 0 to 8.3 at.%, were synthesized by thermolysis of boron-modified poly(methylvinylsilazane). Correlation of the boron content and the thermal stability of these materials in the course of annealing were investigated using high temperature thermal gravimetric analysis (HT-TGA). Furthermore, the initial crystallization of the as-thermolyzed amorphous ceramics was studied by X-ray diffraction (XRD) measurements. The increase of boron content promotes the crystallization of SiC, and inhibits the crystallization of Si 3N 4. Moreover, the ratio of α-Si 3N 4/ β-Si 3N 4 in crystalline ceramic decreases with increasing boron content. Thermodynamic modeling proves the influence of boron content on driving force for crystallization. The available thermodynamic model of amorphous Si–C–N domains, nano-crystalline silicon nitride, and nano-crystalline silicon carbide treated as the separated phases has been used to interpret these results.